A mother mountain lion, known as F92, keeps watch as her kittens, F126 and F127, dine on a deer in the Santa Ana Mountains in 2014. All three cats are the offspring of M86, the only known cougar to cross Interstate 15 and mate on the west side of the freeway — bringing much needed fresh genes into a dangerously inbred population. (Photo courtesy of the UC Davis Wildlife Health Center)

The short, heroic life of the mountain lion known as M86 offers a promise of what could be — and, quite possibly, what must come to pass if the cougars of the Santa Ana Mountains are to survive.

Winston Vickers, left, a veterinarian at the UC Davis Wildlife Health Center and leading researcher and expert of mountain lions in Orange, Riverside and San Diego counties, speaks with research assistants Jamie Bourdon, second from left, Rich Codington, and Trish Smith, an ecologist with The Nature Conservancy, as they stand along a wildlife corridor that follows along the Temecula Creek beneath the I-15 freeway in Temecula, on Tuesday, August 28, 2018. Vickers and others are studying ways to better connect the Santa Ana mountains with a wildlife corridor over or under the I-15 to the Eastern Peninsular Range. (Photo by Mark Rightmire, Orange County Register/SCNG)

A still photograph from a motion activated camera shows mountain lion M86. The now-deceased male is the only lion since at least 2001 known to have crossed Interstate 15 from the east and mated on the west side, bringing fresh genes into the highly inbred population of the Santa Ana Mountains. (Photo Courtesy Irvine Ranch Conservancy)

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Winston Vickers, a veterinarian at the UC Davis Wildlife Health Center and leading researcher and expert of mountain lions in Orange, Riverside and San Diego counties, stands beneath the I-15 freeway in Temecula as he talks about the wildlife corridor that follows along the Temecula Creek on Tuesday, August 28, 2018. (Photo by Mark Rightmire, Orange County Register/SCNG)

Winston Vickers, a veterinarian at the UC Davis Wildlife Health Center and leading researcher and expert of mountain lions in Orange, Riverside and San Diego counties, walks through a culvert beneath the I-15 freeway in Temecula on Tuesday, August 28, 2018. Vickers and others are studying ways to better connect the Santa Ana mountains with a wildlife corridor over or under the I-15 to the Eastern Peninsular Range. (Photo by Mark Rightmire, Orange County Register/SCNG)

A camera mounted in a tree to capture the movements of wildlife for research by Winston Vickers, a veterinarian at the UC Davis Wildlife Health Center and leading researcher and expert of mountain lions in Orange, Riverside and San Diego counties, in Temecula on Tuesday, August 28, 2018. Vickers and others are studying ways to better connect the Santa Ana mountains with a wildlife corridor over or under the I-15 to the Eastern Peninsular Range. (Photo by Mark Rightmire, Orange County Register/SCNG)

A mother mountain lion, known as F92, keeps watch as her kittens, F126 and F127, dine on a deer in the Santa Ana Mountains in 2014. All three cats are the offspring of M86, the only known cougar to cross Interstate 15 and mate on the west side of the freeway — bringing much needed fresh genes into a dangerously inbred population. (Photo courtesy of the UC Davis Wildlife Health Center)

Winston Vickers, left, a veterinarian at the UC Davis Wildlife Health Center and leading researcher and expert of mountain lions in Orange, Riverside and San Diego counties, walks with Jamie Bourdon, research assistant, beneath the I-15 freeway in Temecula along a wildlife corridor adjacent to the Temecula Creek on Tuesday, August 28, 2018. Vickers and others are studying ways to better connect the Santa Ana mountains with a wildlife corridor over or under the I-15 to the Eastern Peninsular Range. (Photo by Mark Rightmire, Orange County Register/SCNG)

Jamie Bourdon, left, and Rich Codington, both research assistants, mount a camera in a tree to capture the movements of wildlife for research by Winston Vickers, a veterinarian at the UC Davis Wildlife Health Center and leading researcher and expert of mountain lions in Orange, Riverside and San Diego counties, in Temecula on Tuesday, August 28, 2018. Vickers and others are studying ways to better connect the Santa Ana mountains with a wildlife corridor over or under the I-15 to the Eastern Peninsular Range. (Photo by Mark Rightmire, Orange County Register/SCNG)

Trish Smith, an ecologist with The Nature Conservancy listens to Winston Vickers, a veterinarian at the UC Davis Wildlife Health Center and leading researcher and expert of mountain lions in Orange, Riverside and San Diego counties, as they stand along a wildlife corridor that follows along the Temecula Creek beneath the I-15 freeway in Temecula, on Tuesday, August 28, 2018. Vickers and others are studying ways to better connect the Santa Ana mountains with a wildlife corridor over or under the I-15 to the Eastern Peninsular Range. (Photo by Mark Rightmire, Orange County Register/SCNG)

Winston Vickers, a veterinarian at the UC Davis Wildlife Health Center and leading researcher and expert of mountain lions in Orange, Riverside and San Diego counties, walks to a culvert beneath the I-15 freeway in Temecula on Tuesday, August 28, 2018. Vickers and others are studying ways to better connect the Santa Ana mountains with a wildlife corridor over or under the I-15 to the Eastern Peninsular Range. (Photo by Mark Rightmire, Orange County Register/SCNG)

Winston Vickers, a veterinarian at the UC Davis Wildlife Health Center and leading researcher and expert of mountain lions in Orange, Riverside and San Diego counties, stands along the I-15 freeway in Temecula on Tuesday, August 28, 2018. Vickers and others are studying ways to better connect the Santa Ana mountains with a wildlife corridor over or under the I-15 to the Eastern Peninsular Range. (Photo by Mark Rightmire, Orange County Register/SCNG)

Jamie Bourdon, a research assistant, writes on the housing of a camera to be mounted in a tree to capture the movements of wildlife for research by Winston Vickers, a veterinarian at the UC Davis Wildlife Health Center and leading researcher and expert of mountain lions in Orange, Riverside and San Diego counties, in Temecula on Tuesday, August 28, 2018. Vickers and others are studying ways to better connect the Santa Ana mountains with a wildlife corridor over or under the I-15 to the Eastern Peninsular Range. (Photo by Mark Rightmire, Orange County Register/SCNG)

Rich Codington, a research assistant, mounts a camera in a tree to capture the movements of wildlife for research by Winston Vickers, a veterinarian at the UC Davis Wildlife Health Center and leading researcher and expert of mountain lions in Orange, Riverside and San Diego counties, in Temecula on Tuesday, August 28, 2018. Vickers and others are studying ways to better connect the Santa Ana mountains with a wildlife corridor over or under the I-15 to the Eastern Peninsular Range. (Photo by Mark Rightmire, Orange County Register/SCNG)

M86 is the only lion known to successfully cross the I-15 freeway from the east and mate during the decade and half that wildlife expert Winston Vickers tracked the cats, 2001 to 2016.

A genetic analysis of the 56 Santa Ana Mountains’ lions he tested show virtually no genetic diversity in the population until M86’s arrival, around 2011, from the far vaster wildlife habitat east of the I-15.

With the male cat’s fresh genes came a slight reprieve from the rampant inbreeding threatening the animals’ survival in the range.

M86 fathered at least 11 kittens, of which six are known to be dead and one in captivity. It’s unknown if any are still alive or if they had offspring.

Other lions have tried to follow M86’s migration, young males driven by the need to find their own terrain or face the consequences of older, bigger males who can respond to territorial instincts by killing potential rivals.

Beside M86, six lions are known to have successfully crossed I-15 during Vickers’ study: two males from the east with no known offspring and four males from the west. Others continue to be killed trying — at least three in the past five years, two of them males, have been fatally hit by cars on the freeway near Temecula.

“We know they want to cross,” said Vickers, a veterinarian with the UC Davis Wildlife Health Center and former Orange County resident. “Sometimes they’ll come and sit near the freeway and watch it all day.”

A path for lions

The challenge is to make a safe and inviting wildlife crossing.

Vickers is working with engineering faculty and students at Cal Poly Pomona to come up with alternatives. Preliminary approaches include making the existing bridge over the Temecula Creek more attractive for the animals to cross under, digging an underpass elsewhere or building a wildlife overpass. Such an overpass is the solution being pursued for the similarly isolated cougars of the Santa Monica Mountains.

The urgency of the task is magnified by steadily shrinking wildlife habitat in the Santa Ana Mountains and a corresponding decline in the lion population.

“We know they want to cross. Sometimes they’ll come and sit near the freeway and watch it all day.”

At about 600-square miles, it’s still more than twice the size of the Santa Monicas habitat and, with 15 to 20 adult lions, has about twice as many cats as its Los Angeles counterpart. The core San Ana Mountains’ habitat is part of the Cleveland National Forest, expected to keep it off limits to development for the foreseeable future.

But the edges continue to be nibbled away. Rancho Mission Viejo is expected to build 10,000 homes on the southwestern part of the range, although Vickers notes that developers are incorporating wildlife corridors.

A smaller proposed development just east of the I-15 in Temecula, bringing as many as 1,750 homes, could pose a thornier problem because it’s immediately north of the area Vickers has identified as the ideal wildlife crossing.

The foothills subdivision, known as Altair, could provide an additional deterrent to lions looking for a way to the other side. That concern is fueling an environmental lawsuit against the city seeking to modify or halt the development.

“The city should be strengthening this critical corridor instead of literally putting up barriers to mountain lion movement,” said Vicki Long of Cougar Connection, one of four plaintiffs in the lawsuit.

Suburban cougars

For most of the past four centuries, mountain lions in North America were seen as both a prize-hunting trophy and a livestock-eating nuisance, with bounties offered from the 16th century until Arizona ended its bounty program in 1990.

Protections for the animals — also known as cougars and pumas — have been increasing steadily since the 1960s, including California voters’ approval of a 1990 measure outlawing mountain lion sport hunting.

As a result, the numbers of states with cougars is now growing in North America. Once eliminated everywhere but in the West and south Florida, the cats have reestablished populations in Nebraska, South Dakota, Arkansas and elsewhere, with at least one sighting as far east as Connecticut.

But those hemmed in by the freeways surrounding the Santa Ana and Santa Monica mountains face an uncertain future.

Preliminary modeling suggests they have about a 15- to 20-percent chance of dying off in the next 50 years, according to Vickers, the foremost expert on the Santa Ana cougars, and collaborator John Benson.

That could increase to as much as 95 percent if they begin to display inbreeding depression, which can result in sperm and heart abnormalities, low fertility rates, weakened systems and lower survival rates.

Genetic diversity isn’t the only challenge facing the lions of the Santa Anas. While the Santa Monica Mountains’ lions have more than a 75-percent chance to live out any given year, the annual survival rate of those in the Santa Anas was just 56 percent during Vickers’ study period.

The biggest cause of death in the Santa Monicas is being killed by other lions. In the Santa Anas, it’s being hit by cars — those crashes accounted for 46 percent of the cougar deaths tallied during Vickers’ study period.

A still photograph from a motion activated camera shows mountain lion M86. The now-deceased male is the only lion since at least 2001 known to have crossed Interstate 15 from the east and mated on the west side, bringing fresh genes into the highly inbred population of the Santa Ana Mountains. (Photo Courtesy Irvine Ranch Conservancy)

When M86’s corpse was found near Santiago Canyon Road in 2015, it was too decomposed to determine cause of death but its proximity to the street offered a clue.

“We presumed he was hit by a car,” Vickers said.

M86 was 5- or 6-years old. Life expectancy is usually 8 to 13 years in the wild and up to 20 years in captivity.

Freeways surrounding the the lions’ habitat in Los Angeles and Orange County — the 405, 101, 91, 5 and 15 — are loud, busy and are usually avoided by the cats. But the 241 toll road and Ortega Highway, while relatively high-speed roads, are not as busy as freeways.

Additionally, the two roads cut directly through the animals’ range, creating an often fatal attraction for wildlife.

Vickers worked with the toll road agency to erect fencing to funnel wildlife to underpasses and culverts along a 6-mile stretch of the 241 and no lions have been killed there in the two years since.

Now, he’s turned his energy to the need for genetic diversity and safe passing over — or under — the I-15.

Solutions

Walking under the bridge over Temecula Creek, it’s clear that smaller animals pass through the densely vegetated area. Vickers points out raccoon and coyote tracks as well as a tree felled by a beaver.

But he notes the noise from above — the sound of tractor trailers and motorcycles can exceed 100 decibels under the bridge. Additionally, the city periodically clears out homeless camps from the area.

Winston Vickers, a veterinarian at the UC Davis Wildlife Health Center and leading researcher and expert of mountain lions in Orange, Riverside and San Diego counties, stands beneath the I-15 freeway in Temecula as he talks about the wildlife corridor that follows along the Temecula Creek on Tuesday, August 28, 2018. (Photo by Mark Rightmire, Orange County Register/SCNG)

“The lions will come and stop about 50 or 60 yards away,” said Vickers, whose assistants were installing two new motion-detecting cameras to better study the lions’ behavior when they approached the bridge. “They’re deterred by a combination of things: sound, light, human presence.”

Among ideas being considered for the underpass are clearing out some of the vegetation — making it more attractive to deer, which would attract lions — and a barrier to dampen the freeway noise.

If they were to make a new underpass to the south of the bridge, the challenge is digging under eight lanes of traffic while leaving a light at the end of the tunnel — requisite for attracting the lions.

And a bridge could be costly. The Los Angeles wildlife overpass is estimated to cost at least $40 million, with a private fundraising effort at $6 million so far.

However, Vickers also points to such bridges built in Arizona at a cost of about $4.8 million in 2011.

Is it worth the money to save lions who are largely clandestine loners, rarely seen by humans? Vickers describes the lions, the apex predator in the area, as a linchpin in the mountain range’s ecology.

He points to the deer of Arizona’s Kaibab Plateau as an example.

Over three decades in the early 20th century, predators — including 816 mountain lions — were killed in an effort to increase the number of mule deer available to hunters in that area. The resulting explosion in the deer population decimated grazing grounds and the animals began starving to death.

“It’s taught in ecology courses as a classic example and it’s not a situation we want to replicate,” Vickers said.

Vickers would also prefer not to repeat the situation in south Florida, where the cat of many names is called a panther. With the isolated population dying off because of inbred depression, eight female lions were brought in from Texas in the mid-1990s and revived the population.

But the state Department of Fish and Wildlife’s policy is not to relocate animals, with concerns including the possibility of a relocated lion killing a person and resulting in publicity blowback. Additionally, if relocation becomes necessary, it would probably require ongoing relocations, Vickers said.

“The advantage with a bridge or tunnel is that other species benefit from it,” he said. “And in the end, you probably wind up spending more (for relocations) than with structure.”

But Vickers doesn’t rule out the possibility of relocations.

“It’s a last resort,” he said. “My main collaborator, Walter Boyce, and I debate the best approach frequently, but in the end it is the public and how much they value the continued presence of mountain lions that will be the last word.”

Martin Wisckol covers coastal environment and development. Previously, he spent two decades as politics reporter and columnist for the Orange County Register. He’s also held reporting positions in Miami, Jacksonville, Detroit and his hometown of San Diego, with an emphasis on land use and urban planning. He is a lifelong surfer and has spent most of his life on the coast. His work has been honored by the Society of Professional Journalists, the National Headliner Awards, the California Newspaper Publishers Association, the Florida Press Club and the American Planning Association Florida Chapter.